US Patent Application 20020101587 teaches an optical system that can determine the spectra of all points in a two-dimensional scene. However, each ray only passes through the sample once; this means that many different rays pass through the same sample region at a large number of differing angles.
U.S. Pat. No. 5,818,046 teaches a combination of mid-infrared transparent elements with new element geometry, new design of the optics and a new radiation path. Specifically, radiation emerges from an IR microscope objective and is then reflected at the sample before being reflected either back to the microscope objective or to a detector. Because the radiation is focused only at a single point and is divergent everywhere else, this design is unworkable for multiple passes through a sample.
U.S. Pat. No. 6,141,100 teaches a single-bounce ATR method that is suited for optically thick, highly absorbing samples.
U.S. Pat. No. 5,965,889 teaches a single bounce, non-imaging internal reflection element which focuses divergent input radiation to a small sample area.